| 鄂尔多斯盆地西缘上奥陶统拉什仲组内波和内潮汐沉积成因分析 |
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| 引用本文： | 李向东,魏泽昳,陈洪达.鄂尔多斯盆地西缘上奥陶统拉什仲组内波和内潮汐沉积成因分析[J].地质学报,2023,97(4):1278-1294. |
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| 作者姓名： | 李向东 魏泽昳 陈洪达 |
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| 作者单位： | 1） 昆明理工大学国土资源工程学院，云南昆明，650093；
2） 自然资源部深地动力学重点实验室，中国地质科学院地质研究所，北京，100037 |
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| 基金项目： | 本文为自然资源部深地动力学重点实验室开放课题基金（编号 J1901- 16）和国家自然科学基金项目（编号 41272119）联合资助的成果。 |
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| 摘 要： | 虽然地层记录中的内波和内潮汐沉积研究已有30年的研究历史，但尚未涉及深水环境中内波和内潮汐成因研究，不利于对深水复杂水动力环境下各种流体交互作用的深入研究，同时由于已发现研究实例中缺乏生物化石和遗迹化石，从而在很大程度上限制了对内波和内潮汐沉积和油气生成及运移之间的关系研究。本文以鄂尔多斯盆地西缘北部桌子山地区上奥陶统拉什仲组深水沉积为研究对象，在详细的野外观察基础上，采用沉积地球化学和沉积学相结合的方法对该组中发育的内波和内潮汐沉积进行了综合研究。结果表明：拉什仲组中的双向交错层理和浪成波纹层理可相互伴生，多发育在完全或近于完全的鲍玛序列Tc段，其寄主岩性主要为灰绿色薄-中层细砂岩、粉砂岩、黏土质粉砂岩和粉砂质黏土岩；沉积时水体介质具有海水性质总体上不明显、氧化-还原分层、盐度倒置、不受热液影响和水动力较强等现象。结合拉什仲组存在的浊流反射现象认为：拉什仲组沉积于局限海深水斜坡至盆地环境，其内波和内潮汐的形成与低密度浊流反射形成的密度跃层密切相关，具有事件性作用特征，并伴生有大量的生物化石(笔石)及遗迹化石。这种新型内波和内潮汐沉积对于深水牵引流沉积油气勘探具有...
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| 关 键 词： | 内波和内潮汐沉积 浊流沉积 遗迹化石 上奥陶统 鄂尔多斯盆地 |
| 收稿时间： | 2021/8/30 0:00:00 |
| 修稿时间： | 2021/10/12 0:00:00 |
Genetic analysis of internal- wave and internal- tide deposits in the Upper Ordovician Lashenzhong Formation, western Ordos basin |
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| Li Xiangdong,Wei Zeyi,Chen Hongda.Genetic analysis of internal- wave and internal- tide deposits in the Upper Ordovician Lashenzhong Formation, western Ordos basin[J].Acta Geologica Sinica,2023,97(4):1278-1294. |
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| Authors: | Li Xiangdong Wei Zeyi Chen Hongda |
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| Abstract: | Although nearly thirty years of research on internal- wave and internal- tide deposits in stratigraphic record are available, there is a lack of studies on the origin of internal- waves and internal- tides. This has seriously limited further research on fluid interactions between different flows in deep- water complex hydrodynamic conditions, and understanding the relationship between internal- wave and internal- tide deposits and hydrocarbon generation and migration, further aggravated by the lack of biological and trace fossils.Here we focus on the deep- water deposits of the Upper Ordovician Lashenzhong Formation in the Zhuozishan area of western Ordos basin, and comprehensively investigatetheir internal- wave and internal- tide deposits by combining sedimentary geochemistry and sedimentology based on the detailed field work. The results show that the bi- directional cross- laminations and wave- ripple laminations could exist have together and were mainly developed in the Tc division of complete or nearly complete Bouma succession, wherethe host lithologies are grayish green thin- to medium- bedded fine- grained sandstones, siltstones, argillaceous siltstones and silty claystones. The characteristics of depositional aqueous media include fewer seawater properties in general, oxidation- reduction stratification, salinity inversion, no effects of hydrothermal fluids and relatively strong hydrodynamic force. Combined with the existing fact of turbidity current reflections, these results perhaps suggest that the Lashenzhong Formation was deposited in the slope to basin plain environments of confined sea, and their internal- wave and internal- tide deposits have obvious characteristics of event action which could have co- existed with large biological (graptolite) and trace fossils because of the pycnoclines in which the internal- waves and internal- tides were formed and related to the reflection of turbidity currents rather than thermocline. The new type of internal- wave and internal- tide deposits discovered in this study have an important significance for oil- gas prospecting of deep- water tractive current deposits. |
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| Keywords: | internal- wave and internal- tide deposits turbidity currents deposits trace fossils Upper Ordovician Ordos basin |
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